Plasma cutting is a process that is used to cut steel and other metals using a plasma torch. An inert gas is blown at high speed out of a nozzle and at the same time an electric arc is formed through that gas from the nozzle to the surface being cut turning some of that gas to plasma. The plasma is sufficiently hot to melt the metal being cut and moves sufficiently fast to blow molten metal away from the cut. Plasma cutting can be used to cut both thin and thick materials. Plasma cutting is often used to cut 60 to 80 mm thick steel but the technique has been known to cut steel up to 300 mm thick.
These days the quality of plasma cutting is enhanced by the use of computer numerical controlled (CNC) machines that robotically control the movement of the cutting torch.
There has also been an increasing demand for more sophisticated cuts that have bevelled edges and for these type of cuts it is known to use five axes cutting heads. A five axes cutting head incorporates a conventional three axis machine that mounts the cutting head assembly in such a way that it can move along an x-y plane and perpendicularly along a z axis, that is, towards and away from the work piece. In this manner the plasma jet is moved along the designated path in an x-y plane and is raised and lowered relative to the work piece. Five axes machines operate in a similar manner but also provide movement about two additional rotary axes, usually one horizontal axis and one vertical axis, so as to achieve in combination with the other axes degrees of tilt and swivel.
In CNC machines, computers are used to control the interrelationship between the movement about the five axes to provide high quality cuts taken from a drawing. Many five axes cutting heads are exceedingly complex and thus very expensive.
This invention relates to a simplified mechanism that provides the necessary control to provide a bevelled edge on a cut by a plasma cutter.